Various types of protection circuits against Electrostatic Discharge (ESD) are known. ESD may be a discharge from an electrostatically charged human or machine to a semiconductor device, a discharge from a charged semiconductor device to earth, and the like. When the ESD occurs in a semiconductor device, a large amount of electric charge flows as a current from a terminal into the semiconductor device and the charge increases the high voltage inside the semiconductor device, which may result in a dielectric breakdown of the internal devices and a fault of the semiconductor device. Especially, in the case of a semiconductor device for automobile use, the device may be affected by an instant surge caused by an inductive load of a motor or a relay and the like, and therefore, protection of the device against ESD, while maintaining operating voltage to the vehicle components is important.
While, in the case of using a resistor-capacitor (RC) timer power clamp, and the like, as the ESD protection circuit, a shunt transistor turns on, to absorb the charge, thereby lowering the power voltage. According to this, when the operation of the protection circuit lasts for a long time, a malfunction may happen in the internal circuit caused by the drop of the power voltage, or a breakdown may happen in the shunt transistor because of the extended operation of the shunt transistor.